Check box to add an additiona fee

I’m having trouble with
I am looking to try to add an option to my products without changing the actual variations. For example, I want to add a checkbox or a way if the customer wants to select this additional product feature for $2.00, they would select it, and the fee would be added to their cart. Same for other products, but different charge. I don’t want to edit the variations however. Any suggestions would be welcomed. Thanks

If you only need a checkbox that adds a fixed fee, you can probably do it with Velo, but I’m not sure on the specifics.

Another option, if you don’t want to code it, is an app I recently published called Better Product Options. It lets you add checkboxes, add-ons, dropdowns, buttons, file uploads, text fields, and others, each with optional price adjustments. Here’s an example:

Just a note: It does not create product variants.